The present invention relates to flush valves for use with plumbing fixtures such as toilets, and more specifically to improvements in the bushing of the actuating handle assembly that will provide for user-selectable, dual mode operation of the flush valve.
Conservation of water resources in the use of toilets can be achieved by allowing a user to select the volume of water required to clean the fixture. For liquid waste a reduced flush volume is adequate. For solid waste a full flush is necessary. Based on the user's determination of whether a larger or smaller flush volume is appropriate to clean the bowl, a flush valve can be operated to provide a larger or smaller volume. Flush valves of this type can be designated dual mode flush valves.
The prior art includes dual mode flush valves. U.S. Pat. No. 2,738,946 has a handle assembly which allows a user to choose either a low volume flush or a full volume flush depending on the axial direction of handle activation. The flush handle assembly includes a plunger having a U-shaped member attached to the inner end thereof. The U-shaped member surrounds the bottom of the relief valve sleeve with legs which have different lengths. Upon activation of the handle one of the U-shaped member's legs will engage the relief valve sleeve and unseat the relief valve. The resulting upward movement of the relief valve will cause the sleeve to clear the leg of the U-shaped member and reseat. Reseating will happen at different times due to the different lengths of the legs. Accordingly, the relief valve reseats either later or sooner depending on which leg engaged the sleeve. Timing of the relief valve closure is one of the factors which governs the length of time the flush valve is open. Therefore the relief valve closure can be used to control how much water flows through the valve during a flush. In this construction the plunger moves only along a horizontal axis regardless of how the handle is actuated. Also, pushing or pulling the handle in a horizontal plane will not activate the valve.
Another attempt to create a dual mode flush valve is shown in U.S. Pat. No. 4,134,570. This valve shows various ways to limit the actuating handle movement, with the intent of limiting the amount of horizontal plunger travel when the user wants to select the minimum flush volume. However, there is no provision for altering the relief valve reseating time. Whether the relief valve sleeve is tilted a small or large amount, the relief valve still cannot reseat until either the diaphragm lifts the sleeve clear of the plunger or the user releases the handle. Therefore, this construction will either fail in practice to produce significant differences in flow volumes or the flow volume will depend on how quickly the user releases the actuating handle. The latter will result in variable and unpredictable flush volumes or incomplete opening of the valve.